Permalinks on Wordpress

In short, I can't get them to work. I've tried many different fixes, but here's how it goes:

1) I install Wordpress via one-click. It works fine.

2) I go to the Permalinks page on WP options, and input a structure like:

/%year%/%monthnum%/Úy%/%postname%/

and many similar combinations.

3) It tells me that it can't write to my .htaccess file, so I:

3a) Make a blank .htaccess file with 666 permissions in both the root of the blog directory (/wordpress) and in the site directory (/). Both directories are also group writeable. This doesn't work - Wordpress still says it can't write to .htaccess.

3b) Make my own .htaccess file with the code it supplies. This doesn't work - when I click on permalinks, I just get a 404 returned.

4) I give up, and use a structure like:

/index.php/%year%/%monthnum%/Úy%/%postname%/

5) This also doesn't work - instead of a 404 when I click on permalinks, I get a "No input file specified" error message.

I've gone on the web and found various bits of info referring to this problem, or problems like it, but I haven't found a fix that works. I can't figure out what's going on here - it seems like mod_rewrite just isn't working for me, but I can't tell. I've emailed Dreamhost tech support, but have had no answer.

Am I forever destined to be without permalinks, or is there something really simple that I'm missing here?